In recent years, a wireless power transmission system including a power transmission apparatus which transmits electric power in a wireless manner without connection by a connector and a power reception apparatus which receives electric power supplied from the power transmission apparatus has been widely used. PTL1 discloses power transmission performed by a power transmission apparatus to a plurality of power reception apparatuses.
When a power reception apparatus operates using electric power received by wireless power transmission, the electric power to be received by the power reception apparatus momently changes in accordance with a state of the operation. Since power reception amounts of the power reception apparatuses change, there arises a problem in that, when a single power transmission apparatus simultaneously transmits electric power to a plurality of power reception apparatuses, reception power of one of the power reception apparatuses changes in accordance with change of power consumption, and therefore, reception power of the other power reception apparatuses also change. For example, while a power transmission apparatus transmits electric power to first and second power reception apparatuses, power consumption of the second power reception apparatus is reduced, and accordingly, reception power is also reduced. In this case, surplus of electric power to be supplied to the second power reception apparatus is generated due to change of the power consumption of the second power reception apparatus which causes an overvoltage state. It is possible that a wireless power transmission circuit of a power transmission apparatus and a wireless power transmission circuit of the first power reception apparatus in which power consumption thereof does not change are destroyed due to the overvoltage. Furthermore, while electric power is supplied to the first and second power reception apparatuses, power consumption of the second power reception apparatus increases, and therefore, reception power is also increased, for example. In this case, reception power is increased with the change of the power consumption of the second power reception apparatus and electric power to be supplied to the first power reception apparatus runs out, and accordingly, an instantaneous interruption state of electric power is entered. When the instantaneous interruption occurs, operation of a load operated by electric power received by the first power reception apparatus in which the consumption power does not change may fail.